Spark-plug.



L. P DIXON. SPARK PLUG.

APPLICATION FILED SEPT-H. 1914.

Patented July 18,1916.

W 8 FM m MW 1 m f y F LAURENS P. DIXON, OF NEW YORK, N. Y.

SPARK-PLUG.

Specification of Iietters Patent.

Patented July s, 1916.

Application filed Septemberl l, 1914. Serial N 0. 861,177.

' To all whom it may concern:

Be it known that I, LAURENS P. DIXON a citizen of the United States, and a resident of New York, borough of Manhattan,

'county and State of New York, have invented certain new and useful Improvements in Spark-Plugs,'of which the following is a specification.

This invention relates to what are known 'as spark-plugs for internal combustion motors, with more particular reference to the casings thereof.

It is well known that among the difficulties which have heretofore been encountered in connection with spark-plug ignition systems are those of overcoming conditions which result in short-circuiting, due either to the accumulation of carbonor other foreign matter on the points of the terminal electrodes, or to the accumulation of oil, grease or even water, with possibly a certain amount of soluble or insoluble matter, form ing a coating on the exterior of the insulator and the exposed parts of the plug. With interior short-circuiting, the present invention has nothing to do, other than to provide a construction which embodies the best of wellknown principles in a simple, compact, efficacious and dependable manner, the principal object of this invention being the provision of a spark-plug and casing so constructed I as to minimize exterior short-circuiting. Incidental to the above, although hardly less important from a commercial view-point, I have in view the provision 3 is a .top planv view thereof; Fig. 4 is a transverse section taken substantially on the line 44 of Fig. 2; Fig. 5 is a fragmentary elevation of the casing with its retaining sleeve-gland, the inclosedinsulator and the central electrode, as hereinafter described in detail, and Fig. 6 is a vertical central section of the upper part of a plug showing a modification of the preferred form of my invention.

Referring now to the drawings in detail, numeral 10 designates the body portion of a casing of preferably cylindrical form, which is molded" from any desired self-hardening plastic materialpossessing,when set and dry, and possibly glazed, the essential qualities of high electrical resistance, high caloric resistance and a high degree of water resistance, of which materials on compounds there are many well-known kinds. This body portion 10 of the casing is designed to be molded directly on the upper end of the sleeve-gland 11, which is provided with a preferably integral upwardly-projecting L- shaped collet 12 around which said casing is molded to form a permanent and tight connection. This permanent union between casing and sleeve-gland forms one of the im"- portant elements of my invention.

The usual porcelain insulator 13 is of common and well-known design, projecting in the usual manner down into the preferably rust-proof steel body 14, where it is provided with an enlarged portion 15 forming annular shoulders adapted to be clamped between an interior shoulder on the body 14 and the lower end of the sleeve gland 11 the usual manner with the enlarged portion 18 and is screw-threaded at its upper end for the reception of the retaining nut 19, whereby said electrode may be permanently and rigidly secured in said insulator.

The casin 10 is suitably apertured forthe reception 0' the insulated wire 20 which leads from whatever source of electric energy may be employed, the aperture proper being formed by the reduced portion of a comparatively large bore 21 to which I prefer to give increased length through the pro vision of a boss 22 on the side of the casing. The larger portion of this bore forms a pocket or recess for the reception of a flexible washer 23 snugly fitted on the insulated wire 20 and slightly greater in diameter than the diameter of the bore 21. make this washer of ordinary commercial soft rubber, whereby, when said washer is mounted on the wire, with a central hole slightly less in diameter than the diameter I prefer to and thus forming a water-tight connection between said wire and said casing. It will be noted that the contour'of this washer after distortion is such that it will readily" resist exterior fluid pressure and prevent the ingress of fluids and foreign matter to the, interior of the casing, and yet Wlll readily yield to internal pressure should any of the expanding gases force their way into the casing. The exposed end of the terminal of the wire 20 is flooped around the rod 17, above the nut 19, in the usual manner, and preferably clamped thereto by means of a sleeve 24 which is interiorly screw-threaded to mesh with the threads at the upper end of said rod. I have shown this sleeve provided with a slot atits upper extremity for the reception of the edge of the blade of a screw-driver, or other suitable tool,-to facilitate manipulation of said sleeve and secure proper electrical connection between the wire and the central electrode.

The body portion 10 of the casing is provided witha cap 25 of the same material or composition, the upper end of said body portion being preferably interiorly recessed or notched and said cap being provided with a boss or enlarged major middle portion telescoping and fitting in said recess to form, in

connection ,with a suitable packing ring or gasket 26, a more nearly fluid-tight joint. Into this cap 25 is molded the nut 27 ,7 interiorly threaded to mesh with exterion threads on the sleeve 24. It will be apparent that after the interior electrical connection has been made between the wire 20 and the rod 17 the cap 25 may be screwed down in (place, this operation not only serving to effect the sealing of the casing against the ing'ressof foreign matter, but also performs the function of a lock or jam nut to more tightly bind or clamp the terminal of wire 20. I have shown the cap 25 milled for the purpose of facilitating manipulationthereof by- 'hand.

' In Fig. 6, I have shown a slight modification of the preferred form of my invention. In the preferred construction, asshown in *Fig. 2, I am employing the'sleeve 24 merely for'the purpose of facilitating the making of the electrical connection, but it will be apparent that I may, if I desire, employ a nut 30 (Fig. 6) cooperating with the nut 19 inthe usual manner to establish the electrical connection, and make the interior threads of the nut 27 mesh with the threads of the upper portion of the electrode 17, thus establishing a direct connection therewith to secure the cap 25 firmly and tightly in place. :This construction is "somewhat simpler than that shown in the other figures of the drawings, although possibly not so-easy to assemble and adjust.

The body 14 is designed to be screwed into the cylinder of the motor in the usual manner, and carries at its extremity the terminal electrodes 28 28, the points of which are brought into proximity with the terminal 29 of the central electrode to provide spark gaps of proper dimensions, b

.With respect to my invention, it will be apparent that I have provided a spark-plug whichfi's so incased as to practically eliminate all possibilityof exterior short-circuiting. While this frequently results from deposits of oil and greasein motors designed for any purpose, it is particularly prevalent in connection with marine motors where spray, fog and even highhumidity may cause short-circuiting through a thin coating of water over the ordinarily exposed parts of the plug. 1

I claim as new and desire to secure by Letters Patent: I

1. In a spark-plug, the combination, with a gland connecting the metal body and the insulator for the central electrode, of an exterior shell consisting entirely of insulating material, said shell including a removable cap and completely incasing and exteriorly insulating the feed-wire connections.

2. In a spark-plug, the combination, with a gland connecting the metal body and the insulator for .the central electrode, of an exterior shell consisting entirely of insulating material rigidly secured to said gland, said shell including a removable cap of' the same material and the whole completely incasing and insulating the feed- Wire connections.

3. In a spark plug, the combination, with a gland connecting the metal body and the insulator for the central electrode, of an exterior shell consisting entirely of insulating material carried by said gland, said ,shell including a removable sealing cap and the whole forming a shell completely insaid casing including a cap of similar material and said cap including means for interiorly securing the same in place.

5. In a spark-plug, the combination, with a gland connecting the metal body and the insulator for the central electrode, of an exterior insulating casing of self-hardening plastic material molded upon saidgland,

said casing including a cap of similar material and said cap having molded therein a nutfor securing the same in place through.

the medium of the central electrode.

6. Ina spark-plug, the combination, with a gland connecting the metal body and the insulator, of an exterior insulating casing secured to said gland, said casing including a removable sealing cap, a central electrode threaded at its upper end for the reception of the retaining nut and aninteriorly I threaded sleeve cooperating with said nut to clamp the Wire terminal therebetween and establish an electrical connection, said sleeve being also exteriorly threaded to receive a cap-retaining nut secured within said cap.

7 In a spark-plug, the combination, with a gland connecting the metal bodyand the insulator, of an exterior casing of self-hardening plastic material molded upon said .gland, said casing including a cap of simi-' .ing also exteriorly threaded to receive a cap-retaining nut around which said cap is molded.

8. In a spark-plug, thecombination, with the interinsulated conductors to the terminals at the spark gap, of an exterior shell consisting entirely of insulating material completely incasing the feed-wire connections, a portion of said shell being removable to permit access to the interior thereof without disturbing said connections.

'9. In a spark-plug, the combination, with the interinsulated conductors to the terminals at the spark ap, of an exterior insulating shell comp etely incasing the feedwire connections, said shell being provided I with an aperture for the insertion of the feed-wire terminal, and a washer of yielding material on said terminal of such dimensions as to be distorted when forced into said aperture.

10. In a spark plug, the combination,

'with the interinsulated conductors to the terminals at the spark plug gap, of an exterior insuflating shell completely incasing the feed-wire connections, said shell consisting entirely of insulating material and being provided with an aperture for the insertion of the feed-wire terminal, and a .Washer of yielding material on said terminal'of such dimensions as to be distorted when forced into said aperture.

' 11. In a spark plug, the combination, with the interinsulated conductors to the terminals at the spark gap, of an exterior insulating shell completely incasing the feed-wire connections, said shell consisting entirely of insulating material and a portion thereof being removable to permit access to the interior. ofsaid shell, and said shell being provided with an aperture for the insertion of the feed-Wire terminal, and a washer .of yielding material on said terminal of such dimensions as to be distorted when forced into said aperture.

In testimony ofthe foregoing, I have hereunto set my hand in the presence of two Witnesses.

LAURENS P. DIXON. Witnesses i J OHN C. KOPF, AARON GINSBURGH, 

